Overgrips are consumables. They are not meant to last weeks. If the surface feels slick, shiny, or uneven, grip performance is already compromised. Sweat absorption drops quickly, and players unconsciously start squeezing the handle harder to compensate.
In humid or hot conditions, some players change overgrips every session. In dry indoor environments, an overgrip may last a few sessions longer. The key signal is not time — it’s feel. If you notice the racket moving slightly in your hand on volleys or overheads, the overgrip is already overdue for replacement. If you want to know more, read this
manual.